diff -Naur rejoystick-0.8.1/src/main.c rejoystick-0.8.1.patched/src/main.c
--- rejoystick-0.8.1/src/main.c	2008-03-23 10:38:22.000000000 -0400
+++ rejoystick-0.8.1.patched/src/main.c	2022-03-15 21:28:38.753577677 -0400
@@ -137,12 +137,11 @@
 
 	pthread_t	sdl_thread;
 
-	char*		home;
-	char*		keyfile;
-
-	home = (char*)getenv("HOME");
-	keyfile = KEYFILE;
-	filename = strcat(home, keyfile);
+	const char * home = getenv("HOME");
+	if(!home) error("HOME not set in environment");
+	filename = malloc(strlen(home) + strlen(KEYFILE) + 1);
+	if(!filename) error("Out of memory");
+	sprintf(filename, "%s%s", home, KEYFILE);
 
 	global_argv = argv;
 
